1. Inheritance of Traits: Pedigrees

2. Pedigree definition
Pedigree: a family history that shows how a trait is inherited over several generations
Pedigrees are usually used when parents want to know if they are carriers of a particular disorder
Carriers are heterozygous for a disorder and don’t show symptoms, BUT have the allele to pass on to their offspring

3. Making a Pedigree
Filled in symbols indicate individual is affected with a disorder
Female
Male
Married Couple
Siblings

4. Example of a Pedigree Do any disorders run in this family??
Grandparents
Grandparents
Parents
Aunts, Uncles
Aunts, Uncles
Brother
You
Do any disorders run in this family??

5. Interpreting a Pedigree
What can you tell from a pedigree?
Whether a family has an autosomal or sex-linked disease or disorder
Autosomal disorder: appears in both sexes equally
Sex-linked disorder: allele is located only on the X or Y chromosome. Most sex-linked genes are on the X chromosome and are recessive
So who would have an X-linked disorder more often, boys or girls?
Whether a disorder is dominant or recessive

6. Is this disorder 1) autosomal or sex linked, 2) dominant or recessive?
Grandparents
Grandparents
Parents
Aunts, Uncles
Aunts, Uncles
Sex Linked! (in this case allele is recessive and located on the X chromosome)
Brother
You

7. Is this disorder 1) autosomal or sex linked, 2) dominant or recessive?
Grandparents
Grandparents
Parents
Aunts, Uncles
Aunts, Uncles
Autosomal dominant!
Brother
You

8. Is this disorder 1) autosomal or sex linked, 2) dominant or recessive?
Grandparents
Grandparents
Parents
Aunts, Uncles
Aunts, Uncles
Autosomal recessive!
Brother
You